We have spent years trying to figure out if all humans see colors in the same way. We still have no answer

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Sight is a sense that fascinates many and the source of a question that all or almost all of us have done at some point, whether the colors that we perceive are the same as the colors that others perceive. Science has not (yet) found the answer, but we do know that there are variations in the perception of colors that we can quantify.

To understand these variations it is convenient to have a general idea of ​​how we perceive colors. The key is in some cells, called cones and rods. These are the photoreceptor cells that are part of our retina, which makes up the convergence between our eye and the central nervous system.

These photoreceptor cells they receive light and transform it into impulses that the central nervous system can transmit until it reaches the brain, the organ that ultimately interprets these signals.

There are three types of cones, S, M and L (short, medium, long) depending on which part of the light spectrum they are optimized to see. That is, the S cone is the one that best perceives the short spectrum (blue, violet) while the L perceives the long lengths (orange, red).

They have created an artificial eye that has the same structure as a biological one and that has been able to "watch"

The genetics of people can affect the ranges of light that each of these cones can perceive more or less easily, but it can also affect their general sensitivity. Thus, some people do not have any of the cones, which makes them less sensitive to a certain range of colors. In these cases we talk about dichromatism.

The variation in the “specialization” of each of these cones may imply that two of them (generally M and L) may overlap. In this other case we speak of anomalous trichromatism, since the three cones work but in an unconventional way.

A great variety

“There are many, many combinations” explained neuroscientist Jenny Bosten in an interview for Knowable Magazine. The key is in the molecules that receive light in these cells, the opsins. These are proteins encoded by a region in the DNA that allows the existence of numerous variations. These variations may involve changes in the protein itself, and with it in how our cones capture light.

If there are people with two cones instead of three, it is also possible to meet people with four. In this case, the necessary condition is to have two X chromosomes and it is called tetrachromatism. It is estimated that 50% of women have four cones. However, these work in an underhanded way, which does not generate a special advantage in vision.

The possibilities are so many that there are people who come to perceive colors differently in each of his eyes.

But the cones are not alone in our retina. The human eye also has rods. The cones do their job best in circumstances where light is abundant. The poles, on the other hand, are more efficient when the light is scarce. Rods have their own “sweet spot” of the visual spectrum. in which they are specialized. This is located between the proper point of S and that of M. It corresponds approximately to shades of light blue or cyan. That is, we perceive colors differently depending on the intensity of light that we have to interpret.

That is, the same person can perceive colors differently at different times. The same can happen even throughout our age. Here the person responsible is neither the retina nor the brain but the macula.

External conditions affect our perception of colors in different ways. Here the key is in the cerebral part of the interpretation of color. And an example of this is the optical illusions with which we became familiar a few years ago when a dress went viral due to its colors.

Back then, screens played an important role, but it wasn’t all a matter of digital color adjustments. Both digital devices and our brains adjust the balance of colors. This adjustment process is fully automated in the case of our brain. We are not even aware of it.

Returning to the eyes, experts have found other factors that can affect our perception of color. The lens, for example, changes with age, becoming opaque to blue light. The macula can also hinder cooler tones, so its density is related to the amount of light of certain tones that reaches our retina. Even the color of our eyes can affect how light and color reach our retina

Culture is important when it comes to understanding how we perceive colors, not at a neurological level but yes regarding our understanding of them. The human being has a certain tendency to categorize what he sees around him, and colors are no exception.

But the colors are only infinitesimal fractions within a spectrum, the visible. Simply put, there is no “correct” way to categorize them, and each culture can do it in different ways to make this classification, what is more, it can vary over time.

An example of this is when we talk about redheads. Redheads can have a multitude of shades of hair, but none would fit into the “red” category these days. However it was not always so.

Image | Evie S.

Sight is a sense that fascinates many and the source of a question that all or almost all of us…

Sight is a sense that fascinates many and the source of a question that all or almost all of us…

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